GROUNDBREAKING 2013

On Oct. 21, 2013 a groundbreaking study was published in the prestigious scientific journal, the Proceedings of the National Academy of Sciences of The United States.• The abstract of this study is reproduced below, and accessible at the following link: http://www.pnas.org/content/early/2013/10/18/1314923110.abstract From a policy standpoint, we see this newly published study to be pivotal, because of its relationship to the logic framing Canada’s current policy on neonicotinoids, particularly as projected in the PMRA review recommendations. The framing assumptions and logic of those recommendations can be summarized as follows: (a) at certain levels of exposure, neonicotinoids are toxic to bees (b) exposure levels are highest due to direct exposure via dust during planting season (c) exposure levels during flowering season, due to translocation from seed to flower are below the level of toxicity to bees (d) consequently, the solution lies in modifications to planting equipment and protocols, while keeping neonicotinoids registered for use. The study published on Oct. 21 2013 directly challenges this body of logic and assumptions by demonstrating a link between low (sub-toxic) levels of exposure, impaired bee immune response, and vulnerablility to a lethal virus carried into colonies by the varroa mite. In the context of this new research, low levels of neonicotinoids, systemically translocated during the growing season to plant flowers, can be seen not as a direct cause of colony collapse, but as a root cause. Abstract Large-scale losses of honey bee colonies represent a poorly understood problem of global importance. Both biotic and abiotic factors are involved in this phenomenon that is often associated with high loads of parasites and pathogens. A stronger impact of pathogens in honey bees exposed to neonicotinoid insecticides has been reported, but the causal link between insecticide exposure and the possible immune alteration of honey bees remains elusive. Here, we demonstrate that the neonicotinoid insecticide clothianidin negatively modulates NF-κB immune signaling in insects and adversely affects honey bee antiviral defenses controlled by this transcription factor. We have identified in insects a negative modulator of NF-κB activation, which is a leucine-rich repeat protein. Exposure to clothianidin, by enhancing the transcription of the gene encoding this inhibitor, reduces immune defenses and promotes the replication of the deformed wing virus in honey bees bearing covert infections. This honey bee immunosuppression is similarly induced by a different neonicotinoid, imidacloprid, but not by the organophosphate chlorpyriphos, which does not affect NF-κB signaling. The occurrence at sublethal doses of this insecticide-induced viral proliferation suggests that the studied neonicotinoids might have a negative effect at the field level. Our experiments uncover a further level of regulation of the immune response in insects and set the stage for studies on neural modulation of immunity in animals. Furthermore, this study has implications for the conservation of bees, as it will contribute to the definition of more appropriate guidelines for testing chronic or sublethal effects of pesticides used in agriculture. •The Proceedings of the National Academy of Sciences of the United States of America, usually referred to as PNAS, is the official journal of the United States National Academy of Sciences (NAS). PNAS is an important scientific journal that printed its first issue in 1915 and continues to publish highly cited research reports, commentaries, reviews, perspectives, feature articles, profiles, letters to the editor, and actions of the Academy. (as reported in Wikipedia)